Yeah, I noticed that as well. The problem here is that automated "screenshots" into these predefined avatar sizes require really careful fiddling with the values. Rhyfe's character is rather large (as it's floating), so the game sets a very high anchor point - and when his character then sits, the predefined screenshot region (anchor-point + so and so many pixels) no longer captures the entire character.
It is a bug, but one that I will not fix: Doing so is rather time consuming, for no gain, because I am not going to permit custom player characters again (especially since PvP and several quests expect characters to have specific poses and specific ways to hold items).
